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#include <iostream>
using namespace std;
 
#define GEN_MESSAGE_INVOKER(FuncName) \
        class\
        { \
        public: \
                template <class C> \
                static void Invoke (C &item, decltype (C::FuncName)) \
                { \
                        item.FuncName (); \
                } \
                 \
                template <class C> \
                static void Invoke (C &item, ...) \
                {} \
        } 
 
 
class A
{
        void OnDerp ()
        {
                cout << "Derpin!" << endl;
        }
};
 
class B
{
};
 
template <class I>
void InvokeMessage ()
{
	A a;
	B b;
        I::Invoke (a,0); //0 goes to either ... or the decltype pointer param.
        I::Invoke (b,0);
}
 
int main() 
{
	InvokeMessage <GEN_MESSAGE_INVOKER(OnDerp)>();
	return 0;
}

prog.cpp: In function 'int main()':
prog.cpp:43:17: error: invalid declaration of member template in local class
prog.cpp:43:17: error: invalid declaration of member template in local class
prog.cpp:43:45: error: expected class-name before '(' token
prog.cpp:43:45: error: expected '::' before '(' token
prog.cpp:43:45: error: expected identifier before '(' token
prog.cpp:43:46: error: expected unqualified-id before ')' token

Standard output is empty